Washington: Hillary Clinton's campaign has canceled a Des Moines rally with vice presidential candidate Tim Kaine and former President Bill Clinton in the wake of the overnight killings of two area police officers.

The Clinton campaign announced Wednesday that the event at the Des Moines Social Club was cancelled. Musician Ben Harper was also scheduled to perform.

Bill Clinton and Tim Kaine were still campaigning in Iowa Wednesday. Kaine was set to appear in Dubuque and Clinton had stops planned in Sioux City and Waterloo.

The officers were shot while sitting in their patrol cars early Wednesday in what authorities described as separate ambush-style attacks. Police said they captured a suspect Wednesday morning.

Donald Trump tweeted Wednesday that he was "praying for the families" of the officers.